1. Field of the Disclosure
The present disclosure relates in general to processes for manufacturing 1,1,1,2,2,3-hexafluoropropane. More particularly, the present disclosure relates to the cost effective and environmentally friendly processes for manufacturing 1,1,1,2,2,3-hexafluoropropane in the presence of a catalyst.
2. Description of Related Art
Halogenated compounds, especially fluorinated compounds, such as fluorocarbons and hydrofluorocarbons, have been widely used in the industry as refrigerants, solvents, cleaning agents, foam blowing agents, aerosol propellants, heat transfer media, dielectrics, fire extinguishing agents, sterilants and power cycle working fluids, et al.
Processes for the production of 1,1,1,2,2,3-hexafluoropropane (HFC-236cb) by using tetrafluoroethylene monomer (CF2═CF2 or TFE) and difluoromethane (CH2F2 or HFC-32) as starting materials and using antimony pentafluoride (SbF5) as a catalyst have been described in U.S. Pat. No. 6,184,426.
Current commercially produced TFE is a monomer for use as a starting material in the manufacture of a variety of fluorinated polymer, for example for the manufacture of polytetrafluoroethylene (PTFE)_, among others. The chemistries used in the manufacture of TFE monomer frequently produce a variety of co-products unacceptable in a polymer feedstock, and said TFE monomer manufacturing processes incur significant expense both in equipment and operating costs to remove any such co-products down to low levels to produce high-purity TFE. These purification steps typically increases the production costs of TFE by as much as 5, 10 or even 20%. Such co-products are considered unacceptable in the TFE starting material because of their adverse effect on the properties of the polymer materials produced from the TFE. For example, any number of hydrogen containing fluorocarbons such as pentafluoroethane (CHF2CF3 or HFC-125) and chlorodifluoromethane (CHClF2 or HCFC-22) are considered objectionable in a TFE product intended for polytetrafluoroethylene (PTFE) manufacture. Carbon dioxide (CO2) is also considered objectionable in a TFE product intended for PTFE manufacture. Residues of such objectionable co-products even as low as 10-100 parts-per-billion by volume (ppbv) are considered unacceptable in such a TFE product.
Similarly, processes that produce HFC-32 typically also produce a variety of co-products that can be expensive both in equipment and operating cost to remove from the final HFC-32 product. For example, the chemistries that produce HFC-32 frequently also include fluorotrichloromethane (CCl3F or CFC-11), difluorodichloromethane (CCl2F2 or CFC-12), chlorodifluoromethane (CHClF2 or HCFC-22), and fluoromethane (CH3F or HFC-41).
The need to remove such co-products from a TFE or HFC-32 product also incurs additional expense in the loss of process materials and the need to provide for environmentally acceptable methods of disposition of such co-product streams. For the 1,1,1,2,2,3-hexafluoropropane from TFE and HFC-32, the additional purification costs of the feedstreams of TFE or HFC-32 can combine to be commercially prohibitive for the intended end use of the 1,1,1,2,2,3-hexafluoropropane, e.g. as an intermediate in the production of refrigeration fluid products. Thus, there is a need for a cost effective and environmentally friendly process for the production of 1,1,1,2,2,3-hexafluoropropane.